Method for patterning thermoperforated figures

ABSTRACT

THERMOPERFORATED PATTERNS ARE FORMED IN FABRICS CONTAINING CELLULOSE FIBERS BY PRINTING AN ETCHING AGENT CONTAINING AN ALKALI CHLORATE AND AN ALUMINUM SALT OF STRONG INORGANIC ACID ON THE FABRIC, THEN BY HEATING THE FABRIC TO DECOMPOSE THE CELLULOSE FIBERS WITHOUT CARBONIZING THEM AND REMOVING THE DECOMPOSED CELLULOSE FIBERS BY MEANS OF AN OXIDIZING AGENT SUCH AS SODIUM CHLORITE.

United States Patent M 3,743,478 METHOD FOR PATTERNING THERMO- PERFORATED FIGURES Yoshikazu Sando and Shigeru Mori, Wakayama-shi,

Japan, assignors to Sando Iron Works Co. Ltd., Wakayama-shi, Japan No Drawing. Continuation-impart of abandoned application Ser. No. 384,551, July 22, 1964. This application June 11, 1969, Ser. No. 832,447

Int. Cl. D06m 5/20, 9/02; D06q 1/02 US. Cl. 8114.6 13 Claims ABSTRACT OF THE DISCLOSURE Thermoperforated patterns are formed in fabrics containing cellulose fibers by printing an etching agent containing an alkali chlorate and an aluminum salt of strong inorganic acid on the fabric, then by heating the fabric to decompose the cellulose fibers without carbonizing them and removing the decomposed cellulose fibers by means of an oxidizing agent such as sodium chlorite.

CROSS-REFERENCE TO PRIOR APPLICATIONS This is a continuation-in-part of our icopending application Ser. No. 384,551 filed July 22, 1964 and now abandoned.

SUMMARY OF THE INVENTION In the present invention a composition of a perforative etching paste is used in preparing open-work patterns in fabrics composed of mixtures of cellulose fibers and synthetic fibers or natural animal fibers by printing the fabric with chemicals exerting decomposing or carbonizing action upon the fabric and removing the cellulose fibers lying in the printed parts. The invention makes it possible for the decomposed or carbonized fibers to be removed not by the conventional mechanical treatment but by chemical method without causing damage to the texture and the patterns and indeed with high efficiency. With the decomposition or carbonization thus effected by the paste, it is suitable for the fibers in printed parts to be easily removed by chemical treatment with no injurious effect on the fibers in non-printed parts.

The chemicals generally employed in the process of partial carbonization and perforative etching are aluminum salts of inorganic strong acids. The carbonization effected by AlCl and A1 (SO9 solutions and the like may, of course, be due to the hydrolysis of cellulose fibers catalyzed by the free acid produced through hydrolysis of these salts as well as to the dehydrating carbonizing action arising from the strong hydrophilicity of the acid. However, the degree of hydrolysis of Al (SO is not very great. Moreover, the nonvolatility of H 80, impedes the decomposition of the salt, the concentration of the acid being rather decreased with increasing dryness of printed parts of the fabric. Thus it is practically ditficult for the process of perforative etching to be accomplished by the use of this salt alone. In the case of AlCl which has a strong tendency of undergoing hydrolysis and produces volatile HCl through hydrolysis, the decomposition advances almost completely to produce HCl and A1 (OH) The carbonizing action exhibited by AlCl is quite intense and incomparable to that of -Al (SO It is well known however that AlCl is used only with difiiculty because the use of this salt alone may cause non-printed parts of the fabric to be attacked by the gas of volatilized HCl. Moreover, the printed parts are fully carbonized to the extent that they become nearly blackin appearance. This state may surely be preferable when the removal of printed parts are carried out solely by mechanical means. It is known from experience, however, that this state is a fair obstacle perhaps for the reason mentioned 3,743,478 Patented July 3, 1973 below and reduces that efficiency of removing the printed parts. For all that, it was also confirmed that reducing the amount of A101 employed, so that color change of printed parts advances only to the extent of browning, hardly enables the browned fibers to be removed by any mechanical means or chemical method.

The reason why complete black carbonization is disadvantageous to the chemical method of removing the carbonized fibers may perhaps be as follows:

It is considered that when cellulose fibers are decomposed so that they become depolymerized to the extent of polymerization degree of 5 and less, the decomposition product behaves as soluble in cold or hot water, thus it is unnecessary for the depolymerization to attain to the production of monomeric glucose, to say nothing of so intense decomposition as to produce free carbon. When the printed fibers are brought to a state of elementary carbon, the decomposition product behaves of course as insoluble in water and also as insensitive to the action of chemicals. Moreover, the black carbonized product appears to have a tendency of agglomeraitng into a granular state. If such agglomeration takes place in fact, it will naturally result in the enhancement of the retardation of permeance of chemicals due originally to the insolubility and chemical indestructibility of the carbonization product. This state of things which also retards the decomposing effect of the oxidizing agent upon the parts needing further decomposition, is causative not only of wasting time but also of the loss of chemicals taking place during the decomposition. In this case, some extra operations become necessary such as those needed for mechanically promoting the removal of carbonized films, for example by agitation. For this reason, the chemical removal of printed parts does not require them to be carbonized to the extent that they become blackened.

However, cellulose fibers in printed parts treated with a chlorate such as NaClO or KClO as perforative etching agent in the presence of a small amount of aforesaid aluminum salt of mineral acid and thereby discolored to lightbrown or moderately deep brown have not been completely carbonized but can be removed even by mechanical treatment just as easily as completely carbonized blackened fibers, chemical removal of the browned fibers in printed parts is achieved far more easily than that of the blackened fibers. This fact is considered to be indicative of the fact that the cellulose fibers are not yet carbonized but are already fully decomposed. Further, as compared with the case of using AlCl alone or AlCl and Al (SO jointly, adoption of the present method reduces the danger of the injurious effect of HCl gas upon non-printed parts, thus the present metthod being ascertained to be adoptable in practice.

The chemical reaction in this case is considered to proceed in accordance with the following scheme:

To begin with, the AlCl or Al (SO applied decomposes in its aqueous solution in the following way:

(As the HCl is volatilized, this reaction is considered to be irreversible and to proceed rightward to perfection) or (As the H behaves as nonvolatile, it is considered that this reaction is reversible and the H 80 produced by hydrolysis at the start is decreased as the perforative etching paste becomes dry.)

3 The acid and A1(O'H) thus produced then react with NaClO according to the following scheme:

The HClO thus produced will react with Al(OH) as follows:

The HClO and Al(ClO undergoing thermal decomposition, are disintegrated ultimately into 0, HCl, a certain sort of acid chloride and Al(OH) This nascent oxygen, displaying a strong oxidative effect in a heated state, causes the cellulose fibers to decompose and depolymerize an oxide of cellulose while the HCl produced from HClO and Al(ClO takes the place of A101 or Al (SO to hydrolyze cellulose fibers. This state of things does not cause carbonization but is effective for fully disintegrating ing the cellulose fibers. Concerning the removal of the fibers by the chemical method, the distintegration to browning is rather preferable as compared with complete carbonization for removing decomposed fibers under advantageous condition. This method is regarded as having a double merit, since the browning action of the above specified treatment is also effective in considerably reducing the danger of selectively injuring non-printed parts of the fabric. The AlCl or Al (SO added on this occasion is sufficient when used only in a small amount. Furthere as regards dangerous AlCl an amount close to that theoretically demanded for the NaClO on the basis of the above reaction scheme will do, an amount of or so of that demand in using AlCl alone thus serving the purpose. In certain circumstances the AlCl may be partially replaced by Al (SO Further, as A1 (SO* improves the stability of AlCl in solution, it is also good to use all the three of alkali chlorate, AlCl and Al (SO in combination.

NOTE.Nt limited to Caesar mucilage, gums of low solid matter content are useful.

A fabric composed of a mixture of polyester or other synthetic fibers and cellulose fibers or a fabric made solely of cellulose fibers is printed by applying the etching paste thereon. After drying, the fabric is subjected to dry heating at about 150 C. for several minutes. After washing with water, the printed parts of the fabric can be removed by means of a solution of an oxidizing agent of chlorine line or of another line. Among these oxidizing agents, it is possible to be used hi -C 0 most effectively 4 and efficiently, of this salt will be described in the following:

The mixture is then adjusted to a pH to 3.0-3.5 by means of formic acid or another organic acid.

The aforesaid fabric is padded with this solution and thereafter imbibed liquor is squeezed out to about a liquid content of (NaClO is given in an amount of 1-2% as referred to the weight of the fabric). The fabric is then introduced into a tightly closed series of vessels, heated with steam at 70-90 C, for 10-20 minutes, washed with water, dechlorinated, again washed with water and dried. As a result of carrying out these steps, decomposed fibers in the patterns printed with perforative etching agent are removed with ease and to perfection.

What is claimed:

1. A method of thermoperforating patterns in a fabric composed of cellulose fibers or of a blend of cellulose fibers and non-cellulose fibers, comprising the steps of printing a perforating etching agent on the fabric comprising an alkali metal chlorate and an aluminum salt of a strong inorganic acid, dry heating the fabric printed with the etching agent to elfect decomposition of the printed cellulose fibers without carbonizing the printed cellulose fibers, and treating the decomposed cellulose fibers in an oxidizing solution of sodium chlorite at an elevated temperature for removing completely the decomposed cellulose fibers from the fabric without the need for mechanical removal of the decomposed cellulose fibers.

2. A method, as set forth in claim 1, wherein the aluminum salt of strong inorganic acid is aluminum chloride and the molar ratio of the alkali metal chlorate to aluminum chloride is approximately 3:1.

3. A method, as set forth in claim 1, wherein the aluminum salt of strong inorganic acid is aluminum sulfate and the molar ratio of the alkali chlorate to aluminum sulfate is approximately 6:1.

4. A method, as set forth in claim 1, wherein the alkali metal chlorate is sodium chlorate.

5. A method, as set forth inclaim 1, wherein the dry heating is carried out at about C.

6. A method, as set forth in claim 1, wherein based on a total volume of 1000 cc. the etching agent is composed of sodium chlorate in the range of 30 to 50 g., aluminum chloride in the range of 10 to 20 g., a pasting agent composed of a gum of low solid material content in the range of 400 to 500 g., and the remainder water.

7. A method, as set forth in claim 1, wherein based on a total volume of 1000 cc. the etching agent is composed of sodium chlorate in the range of 30 to 50 g., aluminum sulfate in the range of 30 to 40 g., a pasting agent composed of a gum of low solid material content (45%) in the range of 400 to 500 g., and the remainder Water.

8. A method, as set forth in claim 1, wherein based on a total volume of 1000 cc. the etching agent is composed of sodium chlorate in the range of 30 to 50 g., aluminum chloride in the range of 10 to 20 g., aluminum sulfate in the range of 30 to 40 g., a pasting agent of low solid material content (45%) in the range of 400 to 500 g., and the remainder water.

9. A method, as set forth in claim 1, wherein the etching agent includes a pasting agent composed of a guru of low solid material content.

10. A method, as set forth in claim 1, wherein the oxidizing solution is composed of sodium chlorite in a range of 10 to 20 g., an anionic or nonionic surface active agent or a mixture of said agents in the range of 2 to 5 g., and water in the amount of 1000 cc.

11. A method, as set forth in claim 10, wherein the pH of the oxidizing agent is adjusted to between 3.0 and 3.5.

12. A method, as set forth in claim 11, wherein the pH of the oxidizing agent is adjusted by means of an organic acid.

13. A method of thermoperforating patterns in a fabric composed of cellulose fibers or of a blend of cellulose fibers and non-cellulose fibers, comprising the steps of printing the fabric with a perforating etching agent composed of sodium chlorate and at least one of the group consisting of aluminum sulfate and aluminum chloride, dry heating the fabric printed with the etching agent at about 150 C. for several minutes for effecting decomposition of the printed cellulose fibers without carbonizing the printed cellulose fibers, dry heating the fabric and washing the fabric with water, introducing the fabric into a solution of an oxidizing agent in which sodium chlorite acts as the oxidizing agent and in which the pH of the solution is between 3.0 and 3.5, introducing the fabric into a sealed space and heating the fabric with 6 steam at about to C. for about 10 to 20 minutes, and then washing the fabric with water, dechlorinating the fabric, repeating the washing with water, and drying the fabric.

References Cited UNITED STATES PATENTS 341,927 5/1886 Maerten 8-1 14.6 725,823 4/1903 Amat 8l 14.0 2,390,903 12/ 1943 Von Glahn 8114.6 880,983 3/1908 Fulton 8-114.6

OTHER REFERENCES Mathews, Bleaching and Related Process, 1921, pp. 797-793.

GEORGE F. LESMES, Primary Examiner J. CANNON, Assistant Examiner US. Cl. X.R. 8115, 115.7, Dig. 

